We seek continued support for the Waisman Intellectual and Developmental Disabilities Research Center, a comprehensive interdisciplinary program on IDD spanning the biological, biobehavioral, and behavioral sciences. The Waisman IDDRC brings together 49 PIs from 25 academic departments from the UW-Madison Schools of Medicine and Public Health, Veterinary Medicine, Pharmacy, Agriculture and Life Sciences, Letters and Science, Education, and Human Ecology. This application requests support for an Administrative Core (Core A), providing scientific leadership, program and faculty development, facilitation of interdisciplinary collaboration, and biostatistical and bioinformatics expertise;ad four innovative scientific core services: Research Participation (Core B), providing services, resources, and training in the recruitment of human participants, clinical assessment, and behavioral methods development;Brain Imaging (Core C), providing access to state-of-the-art neuroimaging instrumentation (3T MRI, PET, and microPET scanners for human, non-human primate, and rodent scanning, and an EEG recording system), as well as expertise and tools for image acquisition and analysis;Rodent Models (Core D), providing resources, expertise, and technical services in the generation, cryopreservation, and maintenance of mutant or genetically engineered strains of mice, and advanced behavioral testing facilities for phenotypic characterization;and Cellular and Molecular Neuroscience (Core E), providing cellular and molecular neuroscience technology, training, and expertise, and supporting the generation of iPS cell lines from humans with IDD conditions. We propose to provide core support to 95 research projects headed by 49 PIs organized into three research groups: Molecular and Genetic Sciences, Communicative and Cognitive Sciences, and Social and Affective Sciences. Collectively, the core services and research groups of the Waisman Center IDDRC will stimulate new interdisciplinary IDD research and enhance existing IDD investigations, sharpening our focus on discovery, prevention, and treatment for IDD conditions and improvement of the quality of life of individuals with IDD and their families.